The present invention relates to solid-state image pickup apparatus including a pixel section consisting of a large number of pixels, in which pixel signals corresponding to a full angle of view (field) can be read out at high frame rates.
Conventional XY addressing type solid-state image pickup apparatus are generally constructed as shown in FIG. 1. The solid-state image pickup apparatus shown in FIG. 1 includes: a horizontal scanning circuit 100; a signal readout section 102 having xe2x80x9cmxe2x80x9d units of NMOS transistors 101 connected in X-direction; a vertical scanning unit 103; and a pixel section 105 having pixels 104 arrayed in a matrix of xe2x80x9cmxe2x80x9d units in X-direction and xe2x80x9cnxe2x80x9d units in y-direction.
Vertical select lines G(1), G(2), G(3), G(4), G(5), G(6), . . . G(nxe2x88x921), G(n) connected to the respective pixel rows each consisting of pixels 104 arrayed in X-direction are connected to a vertical scanning circuit 103 having a function for selectively supplying electric potentials to read out the signal. Horizontal select lines S(1), S(2), S(3), S(4), S(5), S(6), S(mxe2x88x921), S(m) connected to the respective pixel columns each consisting of pixels 104 arrayed in Y-direction are connected to the signal readout section 102 for selectively reading the signal out of pixels 104. While the respective gates of the NMOS transistors 101 of the signal readout section 102 are controlled by output pulses "PHgr"H(1), "PHgr"H(2), "PHgr"H(3), "PHgr"H(4) , "PHgr"H(5), "PHgr"H(6), . . . "PHgr"H(mxe2x88x921), "PHgr"H(m) of a horizontal scanning circuit 100, the sources thereof are respectively connected to the horizontal select lines S(1), S(2), S(3), S(4), S(5), S(6), . . . S(mxe2x88x921), S(m) and the drains thereof are commonly connected to an output terminal SIG.
Referring to a timing chart of FIG. 2, the operation will now be explained of the solid-state image pickup apparatus as shown in FIG. 1. FIG. 2 is the timing chart for illustrating operation of the horizontal scanning circuit 100 and readout operation of the signal of pixels 104 when the vertical select line G(1) is selected. Upon inputting of start pulse HST and clock-pulse HCK to the horizontal scanning circuit 100, output pulses "PHgr"H(1), "PHgr"H(2), "PHgr"H(3) , "PHgr"H(4), "PHgr"H(5), "PHgr"H(6), . . . "PHgr"H(mxe2x88x921), "PHgr"H(m) which are driven to H-level for a duration of one period [time T(sec)] of the clock pulse HCK are sequentially outputted from the horizontal scanning circuit 100 in synchronization with the rising edge of the clock pulse HCK.
Since the NMOS transistors 101 included in the signal readout section 102 are turned on only for a time period during which H-level is being inputted to their respective gate, the NMOS transistor 101 corresponding to the respective output pulse is turned on only for the time period during which output pulse "PHgr"H(1), "PHgr"H(2), "PHgr"H(3), "PHgr"H(4), "PHgr"H(5), "PHgr"H(6), . . . "PHgr"H(mxe2x88x921), "PHgr"H(m) of the horizontal scanning circuit 100 is driven to H-level. Accordingly, only for the time periods during which output pulses "PHgr"H(1), "PHgr"H(2), "PHgr"H(3), "PHgr"H(4), "PHgr"H(5), "PHgr"H(6), . . . "PHgr"H(mxe2x88x921), "PHgr"H(m) of the horizontal scanning circuit 100 are driven to H-level, the corresponding horizontal select lines S(1), S(2), S(3), S(4), S(5), S(6), . . . S(mxe2x88x921), S(m) are selected to read the signal out of pixels 104. It should be noted that SIG in FIG. 2 represents the pixel signal read out to the output terminal SIG as shown in FIG. 1, and (1,1), (2,1), (3,1), (4,1), (5,1), (6,1), . . . (mxe2x88x921,1), (m,1) correspond to the array of pixels of the pixel section 105 in FIG. 1.
In the conventional solid-state image pickup apparatus as shown in FIG. 1, if the number of pixels 104 included in the pixel section 105 is increased, the signal readout time corresponding to one frame, i.e., frame rate is prolonged nearly in proportion to the number of the arrayed pixels unless the signal readout time per unit pixel is reduced. For example, if signal readout of a solid-state image pickup apparatus having 2,000 pixels in both horizontal and vertical directions is to be performed at the same signal readout time per unit pixel as a solid-state image pickup apparatus having 640 pixels horizontally, 480 pixels vertically and a frame rate of {fraction (1/60)} sec., its frame rate is ({fraction (1/60)})xc3x97(2,000xc3x972,000)/(640xc3x97480)=0.22 sec. Such frame rate necessitates an exceedingly long time in adjusting the angle of view and focal point of the taking lens even when the above described solid-state image pickup apparatus is used as an image input apparatus of a still camera system for taking still images. An inconvenience is caused when manipulating the system.
In view of the above problems of the conventional solid-state image pickup apparatus, it is a main object of the present invention to provide a high-definition solid-state image pickup apparatus capable of performing readout of the pixel signals corresponding to a full angle of view at a rapid frame rate even when the number of pixels is very large.
In accordance with the present invention, there is provided a solid-state image pickup apparatus including a pixel section having a plurality of pixels arrayed in both or one of horizontal and vertical directions and a scanning circuit for scanning the pixel section, the scanning circuit comprises a scanning section having a plurality of scanning circuit units each consisting of a shift register unit and a signal select unit having a plurality of output terminals, and a scan control section for generating scan control signal for controlling the signal select unit. Output signal of the shift register unit is selectively outputted to the plurality of output terminals of the signal select unit controlled by the scan control signal to form scanning signal of the scanning circuit.
In this manner, output signal of the shift register unit is selectively outputted to the plurality of output terminals of the signal select unit controlled by the scan control signal to form scanning signal. It is thereby possible to perform at a rapid frame rate readout of pixel signals corresponding to a full angle of view even when a high-definition solid-state image pickup apparatus having a very large number of pixels is used. The above main object is thereby achieved.
In one aspect of the invention, the signal select unit includes a plurality of 2-input NOR circuits each having one input terminal to which scan control signal is inputted and the other input terminal connected in common to which output signal of the shift register unit is applied. Scanning signal is provided from the respective output terminal of the plurality of 2-input NOR circuits. In another aspect, the signal select unit includes a plurality of 2-input NAND circuits each having one input terminal to which scan control signal is inputted and the other input terminal connected in common to which output signal of the shift register unit is applied. Scanning signal is provided from the respective output terminal of the 2-input NAND circuits. In yet another aspect, the signal select unit includes a plurality of scanning signal transmitting switches one end of each connected in common to the output terminal of the shift register unit and controlled by scan control signal, a non-select level line for supplying non-select level of the scanning signal, and a plurality of non-select switches disposed between the other end of the scan signal transmitting switches and the non-select level line and controlled by an inverted signal of the scan control signal. Scanning signal is provided from the other end of each scanning signal transmitting switch. By constructing the signal select unit in the manner as described above, it is possible to readily form scanning signal capable of performing at high frame rates readout of pixel signals corresponding to a full angle of view in various modes conforming to the scan control signal outputted from the scan control section.
It is another object of the present invention to provide a solid-state image pickup apparatus capable of performing at high frame rates readout of pixel signals corresponding to a full angle of view by scanning through thinned out pixel signals.
In accordance with the present invention, the scan control section provides scan control signal for causing the output of the shift register unit to be selectively outputted as scanning signal to one terminal of the plurality of output terminals of the signal select unit in a time period during which a select level is being outputted. In another aspect of the invention, the scan control section provides scan control signal for causing the output of the shift register unit to be outputted as scanning signal to a plurality of inconsecutive terminals of the plurality of output terminals of the signal select unit at different timings from one another in a time period during which a select level is being outputted. The above object is thereby achieved.
It is a further object of the present invention to provide a solid-state image pickup apparatus capable of performing at high frame rates readout of pixel signals corresponding to a full angle of view while inhibiting a weakening of signal level and at the same time suppressing spurious signals.
In accordance with the present invention, the scan control section provides scan control signal for causing the output of the shift register unit to be outputted as scanning signal concurrently to all the terminals of the plurality of output terminals of the signal select unit in a time period during which a select level is being outputted. In accordance with another aspect of the present invention, the scan control section provides scan control signal for causing the output of the shift register unit to be outputted as scanning signal concurrently to a plurality of consecutive terminals of the plurality of the output terminals of the signal select unit in a time period during which a select level is being outputted. In this manner, pixel signals are scanned as they are added to one another and readout at high frame rates of pixel signals corresponding to a full angle of view is possible, by causing all the terminals of the plurality of output terminals of the signal select unit to concurrently output scanning signal by means of scan control signal provided from the scan control section, or by causing a plurality of consecutive terminals of the plurality of output terminals of the signal select unit to concurrently output scanning signal by means of scan control signal provided from the scan control section. At even higher frame rates, a weakening in signal level is inhibited and spurious signals can be suppressed by increasing the virtual aperture of pixels, thus achieving the above object.
A still further object of the present invention is to provide a solid-state image pickup apparatus in which signal select units of the same construction can be used to sequentially read out all pixel signals in a similar manner as the conventional apparatus, in addition to readout at high frame rates of pixel signals corresponding to a full angle of view.
In accordance with the present invention, the scan control section is constructed to provide scan control signal for causing the output of the shift register unit to be outputted as sequential scanning signal to the plurality of the output terminals of the signal select unit in a period during which a select level is being outputted. The above object is achieved such that, with signal select units of the same construction, not only readout at high frame rates of pixel signals corresponding to a full angle of view but also sequential readout of all pixel signals similar to that in the conventional solid-state image pickup apparatus is possible, by means of construction where the plurality of output terminals of the signal select unit are caused to output sequential scanning signal by scan control signal provided from the scan control section.